While it's unknown how far along Riley's pregnancy is, what seems clear to us is that the 33-year-old has been holed up for a while! I mean, that bump is pretty prominent in that fitted black dress she'd picked to wear to hubby's premiere.

I love when people, particularly celebs, keep their pregnancy a surprise like that -- they not only have to keep their mouths shut, but really keep their eye peeled for paparazzi in public. Pregnancy is a hard thing to hide!